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      <title>10、Kafka的流量控制与背压机制 - 学习卡片</title>
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      <div class="header">
        <h1>10、Kafka的流量控制与背压机制 - 学习卡片</h1>
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      <div class="card">
        <div class="card-face card-front">
          <div class="card-category">理论</div>
          <div class="card-question">Kafka 是通过哪两个主要层面来实现流量控制与背压机制的？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">理论</div>
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            <div class="card-answer">Kafka 的流量控制与背压机制主要通过两个层面实现：1. Producer端的流量控制，通过参数限制其发送速率；2. Broker端的背压机制，通过限制请求队列大小来避免自身过载。</div>
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          <div class="card-source">来源: 1. Kafka流量控制与背压机制概述</div>
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          <div class="card-category">机制</div>
          <div class="card-question">Kafka Producer 是如何具体实现流量控制的？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">机制</div>
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            <div class="card-answer">Producer 通过 `max.in.flight.requests.per.connection` 参数来限制对单个 Broker 连接上未确认的请求数量。当未确认的请求数达到这个上限时，Producer 会暂停向该连接发送新的请求，直到收到 Broker 的响应，从而实现流量控制。</div>
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          <div class="card-source">来源: 2.3 流量控制实现</div>
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        <div class="card-face card-front">
          <div class="card-category">机制</div>
          <div class="card-question">Kafka Broker 的背压机制是如何工作的？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">机制</div>
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            <div class="card-answer">Broker 通过限制其内部请求队列的大小来实现背压。这由 `queued.max.requests`（最大请求数）和 `queued.max.bytes`（最大字节数）两个参数控制。当队列中任一指标达到上限时，Broker 会拒绝新的请求并抛出 `QueueFullException`，从而向上游（Producer）传递压力。</div>
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          <div class="card-source">来源: 3.3 背压机制实现</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
      <div class="card">
        <div class="card-face card-front">
          <div class="card-category">特性</div>
          <div class="card-question">在 Producer 端，`max.in.flight.requests.per.connection` 参数的默认值是多少？它代表了什么含义？</div>
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          <div class="card-category">特性</div>
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            <div class="card-answer">该参数的默认值是 5。它表示 Producer 与每个 Broker 节点建立的连接上，最多允许存在 5 个已经发送但尚未收到响应的请求。</div>
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          <div class="card-source">来源: 2.3 流量控制实现</div>
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        <div class="card-face card-front">
          <div class="card-category">模式</div>
          <div class="card-question">当 Broker 的请求队列已满时，Producer 会如何响应？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">模式</div>
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            <div class="card-answer">当 Broker 的请求队列满时，Producer 发送的请求会收到一个 `Errors.QUEUE_FULL` 错误响应。Producer 内部的 `Sender` 线程会识别这个错误，并根据 `retries` 参数的配置触发重试机制。</div>
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          <div class="card-source">来源: 4.1 Producer与Broker的交互</div>
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        <div class="card-face card-front">
          <div class="card-category">技术</div>
          <div class="card-question">在对 Broker 进行性能调优时，`queued.max.requests` 和 `queued.max.bytes` 参数应分别依据什么进行调整？</div>
          <div class="card-footer">点击卡片查看答案</div>
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        <div class="card-face card-back">
          <div class="card-category">技术</div>
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            <div class="card-answer">在进行参数调优时，`queued.max.requests` 参数应根据 Broker 的内存大小进行调整，而 `queued.max.bytes` 参数则应根据磁盘 IO 性能进行调整。</div>
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          <div class="card-source">来源: 5.1 参数调优</div>
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        <div class="card-face card-front">
          <div class="card-category">机制</div>
          <div class="card-question">请简述 Kafka Producer 发送消息的核心流程。</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">机制</div>
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            <div class="card-answer">Producer 发送消息的核心流程分为三步：1. 消息被序列化后放入 RecordAccumulator 缓冲区；2. Sender 线程从 RecordAccumulator 中批量获取消息并发送到 Broker；3. Broker 返回响应后，Sender 线程处理响应并触发回调。</div>
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          <div class="card-source">来源: 2.1 发送流程概述</div>
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          <div class="card-category">技术</div>
          <div class="card-question">在 Broker 端，`SocketServer.handleCompletedReceives()` 方法的核心作用是什么？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">技术</div>
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            <div class="card-answer">该方法的核心作用是处理已完成的网络接收。它会解析收到的数据，构建成一个请求上下文（RequestContext），然后通过 `requestChannel.sendRequest()` 方法将这个请求放入请求队列中等待后续处理。</div>
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          <div class="card-source">来源: 3.2 SocketServer.handleCompletedReceives()</div>
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        <div class="card-face card-front">
          <div class="card-category">技术</div>
          <div class="card-question">除了调整核心流量控制参数外，文档还提到了哪两种可以优化 Producer 性能的方法？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">技术</div>
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            <div class="card-answer">文档中提到了另外两种源码级别的优化方法：1. 通过 `linger.ms` 参数优化批量发送，增加消息在缓冲区停留的时间以形成更大的批次；2. 通过 `compression.type` 参数启用或更改压缩算法来减少网络传输的数据量。</div>
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          <div class="card-source">来源: 5.2 源码优化</div>
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